During a recent Netherrealm live stream, the character select screen was shown with every slot filled including the GORO dlc spot. Combined with the additional DLC characters Predator, Tanya, Tremor, and Jason, this confirms a complete core roster of 29 characters.
Kung Lao
Jax
Tanya
Tremor
Predator
Sonya
Liu Kang
Jason
Kung Jin
Ermac
Taskashi Takeda
Jaceline Briggs
Goro
Mileena
Cassie Cage
Sub-Zero
Scorpion
D’Vorah
Kotal Kahn
Ferra & Torr
Raiden
Kano
Reptile
Kenshi
Quan Chi
Kitana
Enron Black
Johnny Cage
Shinnok
In addition it was also mentioned that linking the console game with the mobile version would unlock more character skins for Johnny Cage and Jax. IGN also has a video showing the first 25 minutes of story mode gameplay. In it several characters from previous entries make appearances like Stryker and Sindel, no word on if those characters will be available as DLC later on.
Mortal Kombat X is set to launch on April 14, 2015 for the Xbox One and PS4 with PS3 and Xbox 360 versions to follow in the Summer.